Illumination systems are becoming ever more sophisticated. We witness an evolution in illumination systems where the brightness and/or colours of the illumination have become adaptable.
A system as described in the opening paragraph is known from ‘Real World Dynamic Appearance enhancement with Procam Feedback’ by Toshiyuki Amano and Hirokazu Kato, Procams 2008, Marina del Rey, Calif., Aug. 10, 2008. This known system comprises a camera to allow feedback from the illuminated scene. Such feedback can be used to highlight specific objects or scenes in the interior, but also to perform image enhancement of art objects, like paintings. The system enhances the reality, and provides a clearer, crisper image. Within the concept of the invention an object is any object that is illuminated. Examples of such objects are displays, pictures, paintings, persons, trees, whether alone or in a group, whether as a whole or a segment of a person, tree etc.
The main problem of a reality enhancement lighting system is to get a stable result. A feedback loop between the light recording device and the illumination device leads to an unstable system. For ease of understanding, but not as a restriction, a light recording device will be below sometimes also called a camera and an illumination device a projector. The image projected by the projector on the object changes the appearance of the object as seen by the camera, which leads to further enhancement in the next projected image on the object, which leads to a yet further change of the appearance of the object as seen through the camera etc. This may lead to a runaway effect in which the enhancement keeps on increasing.
Amano et al. offer a solution they call “partial feedback”. The feedback gain is considerably reduced. The reduction in feedback gain keeps the run-away effect in check. Although this apparently leads to a fairly stable system for static scenes it introduces a significant latency of the enhancement system, which makes the system less suited for dynamic scenes (operation theatre, car headlights etc.). Also the known system reacts nervously on changes in ambient illumination due to moving objects in the environment and has problems with edges of objects in an image.
It is an object of the invention to provide an illumination system and illumination method in which one or more of the above problems are reduced.